Simple Calculator in C programing

https://www.youtube.com/watch?v=CW-ewWpUm9M

I am trying to make a simple calculator that works this way. The video provides a demo. I also wrote it out in text.

Enter Operation:

1.) Addition

2.) Subtration

3.) Multiplication

4.) Division

1

Enter First Number:2

Enter Second Number:2

2 + 2 = 4

#include

int main(int argc, const char * argv[]) {

int operation;

int firstNumber;

int secondNumber;

int answer;

printf("Enter your choice of operation: ");

printf("1.Addition ");

printf("2.Subtraction ");

printf("3.Multplication ");

printf("4.Division ");

scanf("%d", &operation);

if ((operation = 1)){

printf("First Number: ");

scanf("%d ",&firstNumber);

printf("Second Number: ");

scanf("%d ",&secondNumber);

answer = firstNumber + secondNumber;

printf(answer);

}

else if ((operation = 2)){

printf("First Number: ");

scanf("%d ",&firstNumber);

printf("Second Number: ");

scanf("%d ", &secondNumber);

answer = firstNumber - secondNumber;

}

else if ((operation = 3)){

printf("First Number: ");

scanf("%d ",&firstNumber);

printf("Second Number: ");

scanf("%d ", &secondNumber);

answer = firstNumber * secondNumber;

}

else if ((operation = 4)){

printf("First Number: ");

scanf("%d ",&firstNumber);

printf("Second Number: ");

scanf("%d ", &secondNumber);

answer = firstNumber/secondNumber;

}

return 0;

}